The present invention relates to a surface inspection apparatus for inspecting a surface of an object to be inspected.
A known surface inspection apparatus projects inspection light on a surface (hereinafter also referred to as an object surface) of an object to be inspected (test object) such as a semiconductor wafer and a glass mask via a reference surface to pick up interference (Moire) fringes formed (occurring) by reflected light from the reference surface and reflected light from the object surface using a pick up device such as a CCD camera, thereby inspecting the object surface (a shape of the object surface) based on the picked up interference fringes.
By the way, when the object allows the inspection light to pass therethrough, interference fringes (hereinafter also referred to as rear face interference fringes) are formed by the reflected light from the object surface and a reflected light from a rear face of the object, and these interference fringes cause noise (disturbance) during the inspection of the object surface.